There is something in physics that does not have a special name like a Newton or a Joule.
It is momentum and can be expressed as mass multiplied by velocity (kg*m/s).
Like energy and matter, momentum is conserved.
If you shoot a gun, there will be a recoil; the bullet goes forward and there is also a force backward.
The greater the force forward is, the greater the opposite force will be, so shooting a shotgun will have more recoil than James Bond’s ppk since the a shotgun shell has greater mass and about the same speed.
Also if you’re ever on a frictionless frozen lake you could throw your boot in the opposite direction of the direction you want to go, and you would end up moving to the edge of the lake (if you disregard friction).
In the real world though there is friction, and losing the toasty interior of the boot might not be the best idea.